During V's ML drama, G compared V's action with Dev. V is new to Singh family. He tried to attract Singh family with his goody goody act. In that way there is a possibility of copying Dev's action to get G's attention. Someone close to Dev must have given his some tips. Surely not anyone from Singh family. That person could be Rana. The level of relationship between Dev and Rana should be revealed. V had connection with everyone who are against Singh family.
V comes to know about Rana's real intention. That is why Rana is now keeping him under mental lost state. Previously V is not cared about what is happening to singh family. Now he is having child's heart and wants to help R.
But how V remembers only certain incidents? How could he forget J if he remembers all these?
Also chance K death occurring after V lost his mental state and he is another witness to Rana's plot.
Or resemblance of action with Dev is real and have some relationship existing between G and V. Like Prime said, possibility of step brother concept.